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LSU KATRINA FLOODWATER STUDY WIDELY MISINTERPRETED, SHOULD NOT LULL RETURNING RESIDENTS INTO COMPLACENCY ABOUT RISKS, SAYS NRDC

EPA and Independent Data Show Toxic Risks Remain in New Orleans; Experts Counsel Precautions for Katrina Returnees

WASHINGTON (OCTOBER 12) -- A study released yesterday by Louisiana State University (LSU), which detected elevated levels of bacteria and chemicals in post-Hurricane Katrina floodwaters, has been widely misinterpreted as giving New Orleans a relatively clean bill of health, according to the Natural Resources Defense Council (NRDC).

Stories in today's newspapers focused mainly on the LSU study's summary, or abstract, which stated that it found many contaminants at levels typical of other floodwaters. The actual data presented in the main body of the study, however, contradicts that characterization, NRDC found. (The LSU study is available as a pdf.)

The national environmental organization cautioned that the LSU study's own data, as well as more comprehensive Environmental Protection Agency and other independent data, show there are in fact significant toxic risks in New Orleans and surrounding areas.

"The scientific information is far from reassuring, said NRDC health expert Erik D. Olson. "All of the data collected so far still show dangerous toxic pollution levels in the air and in dried mud. Now there is also pervasive mold that threatens public health."

Dr. Gina Solomon, an NRDC physician, added that "residents returning to flooded areas should know that there are still very real health risks and that they need to be careful to wear appropriate masks, gloves and protective clothing if they are going to spend much time or start cleaning up in these areas. Children, the elderly, and people with heart or lung disease should stay completely out of these areas for now."

Olson and Solomon toured the devastated area last week to set up an independent sampling study and meet with local officials and residents. An NRDC delegation will return to New Orleans later this week.


Sampling Issues

The study by LSU researchers and private industry consultants took "grab samples" of floodwaters in a few Crescent City neighborhoods on a single day in each neighborhood shortly after Hurricane Katrina. They did not test sediment toxicity, dust from the dried sediment, mold, or air pollution levels -- the major problem for returning residents now that the floodwaters have receded.

EPA and other independent tests show that sediment and rising dust in the area may pose significant health threats. EPA and independent experts continue to recommend that anyone use precautions when spending any significant time in the area. They urge people to wear professional respirators, disposable coveralls, rubber gloves, and boots.

EPA and independent tests have found high levels of lead, arsenic and dangerous bacteria in Katrina floodwaters. They also found elevated levels of particulate matter in the city's air, and levels of benzene -- a carcinogen and nerve toxin -- above those considered safe when people are exposed for two weeks or more. Tests also found some sediment samples contain hazardous levels of lead, chromium, arsenic and petroleum byproducts known as polycyclic aromatic hydrocarbons. .


Reporting Errors

The LSU study's abstract states that the floodwater that covered New Orleans was not unusually toxic and was "typical of storm water runoff in the region." But that conclusion is at odds with data presented in the study's main body, Solomon said.

For example, the LSU study detected benzene at a level nearly four times higher than EPA's drinking water standard. And deep in the paper, the authors state that toxic volatile organic compound "concentrations are 2-3 orders of magnitude higher than those previously reported for stormwater runoff." (See page E.)

Besides finding high levels of benzene, the LSU study also found lead and arsenic at levels "consistently in excess" of EPA drinking water standards in New Orleans' Mid-City district tests. For example, the data shows lead levels in Mid-City floodwaters averaged 28 parts per billion (ppb), double EPA's safe drinking water level, and at one location it reached 111 ppb -- nearly eight times the EPA safe level.

For purposes of comparison, the paper states that lead levels in other recent, non-Katrina-related stormwater events were 1.5 ppb to 58 ppb -- a peak roughly half that of the highest sample in Mid-City after Katrina. The study itself states that lead concentrations in post-Katrina floodwater "were higher than stormwater ranges, Mississippi River water, and the [EPA Maximum Contaminant Level]." (See page F.) Similarly, arsenic levels in the city's Lakeview district averaged three times higher than the EPA drinking water standard, and in Mid-City averaged 4.5 times the EPA standard.


Time Lag

Finally, the fact that the LSU study took samples a month ago suggests that it may have inadvertently under-reported the extent of toxic contamination. LSU and private researchers tested floodwater in the Lakeview district on September 3, and in the Mid-City district on September 7. They collected a smaller number of bottom samples along the 17th Street canal on September 6, 11 and 13. In other words, LSU did only a single day of testing at most locations, soon after Katrina hit, and well before Hurricane Rita reflooded the area.

There is a likelihood that pollution concentrations have increased since LSU took samples, Solomon said. The LSU study itself acknowledges that the longer a pollution source, such as an industrial site, is flooded, the more toxic pollution could leach into the water. (See page F.)

"This LSU study, while in some ways consistent with previous data, should not be viewed as giving the green light for residents to immediately return to the flooded areas of the city," Olson said. "There are still very real health risks, so people need to use common sense and take the necessary precautions."

The Natural Resources Defense Council is a national, nonprofit organization of scientists, lawyers and environmental specialists dedicated to protecting public health and the environment. Founded in 1970, NRDC has more than 1 million members and online activists nationwide, served from offices in New York, Washington, Los Angeles and San Francisco.

Related NRDC Pages
Health Advisory For New Orleans Residents Returning to Their Homes
On the Ground in New Orleans: An NRDC Fact-finding Mission, October 2005
Environmental Policy Discussions After Hurricane Katrina

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